<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>三列布局示例</title>
<style>
  #container {
    display: flex;
    flex-direction: column;
    height: 100vh; /* Full height */
  }

  #header {
    background-color: #333;
    color: rgb(244, 18, 18);
    padding: 10px;
    text-align: center;
  }

  #middle {
    display: flex;
    flex-direction: row;
    flex: 1; /* Take up the rest of the space */
  }

  #column1 {
    background-color: #e37373;
    padding: 20px;
    width: 33.33%; /* Three columns evenly */
    box-sizing: border-box; /* Include padding and border in width */
  }

  #column2 {
    background-color: #ddf008;
    padding: 20px;
    width: 66.66%; /* The middle column is twice as wide */
    box-sizing: border-box; /* Include padding and border in width */
  }

  #column3 {
    background-color: #20f907;
    padding: 20px;
    width: 33.33%; /* Three columns evenly */
    box-sizing: border-box; /* Include padding and border in width */
  }

  #footer {
    background-color: #333;
    color: rgb(9, 164, 254);
    padding: 10px;
    text-align: center;
  }
</style>
</head>
<body>

<div id="container">
  <div id="header">页眉内容</div>
  <div id="middle">
    <div id="column1">第一列内容</div>
    <div id="column2">第二列内容</div>
    <div id="column3">第三列内容</div>
  </div>
  <div id="footer">页脚内容</div>
</div>

</body>
</html>